Most plans for Mars bases make becoming a colonist about as desirable as setting up house in an oil drum, but an MIT team has come up with a plan for a Mars city based on the architecture of a tree. Taking out first place in the Architecture section of the Mars City Design 2017 competition, the Redwood Forest concept is intended to provide settlers with not only protection against the harsh Martian environment, but open public spaces filled with plants and abundant water.

As Sir Elton John said, Mars ain't the kind of place to raise your kids. Though the Red Planet is the most habitable of the planets, aside from our own, in the Solar System, it is still a terribly hostile place. The nighttime temperatures put the Antarctic to shame, the air is only a hundredth the pressure of Earth's and is composed mostly of carbon dioxide, deadly UV radiation rains down during the day, and cosmic rays are present 24/7. It's also dry to the point where the soil is composed of corrosive substances with very unpleasant properties.

Due to these drawbacks, it's difficult to come up with designs for manned outposts that don't look like a collection of tins that make the Amundsen-Scott South Pole Station look like a luxury resort. To break away from this stereotype, the MIT team of nine students led by MIT postdoc Valentina Sumini and Assistant Professor Caitlin Mueller took an interdisciplinary approach that uses location and system architecture, as well as water harvested from the Martian polar ice caps to supply tree-like habitats, for a design capable of housing 10,000 inhabitants in shirt-sleeve comfort.

At first glance, the MIT habitats don't look very tree-like. They look more like giant glass balls sitting on the Martian plains, each housing 50 people. But, like real trees, much of the habitat is below the surface in the form of intricate tunnels that connect the spheres and provide protection from cold, radiation, micrometeorites, and other surface hazards.

"On Mars, our city will physically and functionally mimic a forest, using local Martian resources such as ice and water, regolith or soil, and sun to support life," says Sumini. "Designing a forest also symbolizes the potential for outward growth as nature spreads across the Martian landscape. Each tree habitat incorporates a branching structural system and an inflated membrane enclosure, anchored by tunneling roots. The design of a habitat can be generated using a computational form-finding and structural optimization workflow developed by the team. The design workflow is parametric, which means that each habitat is unique and contributes to a diverse forest of urban spaces."

The habitats rely heavily on water, but not just for drinking, agriculture, or public fountains. It's a key ingredient in making the domes habitable.

"Every tree habitat in Redwood Forest will collect energy from the sun and use it to process and transport the water throughout the tree, and every tree is designed as a water-rich environment," says Department of Aeronautics and Astronautics doctoral student George Lordos. "Water fills the soft cells inside the dome providing protection from radiation, helps manage heat loads, and supplies hydroponic farms for growing fish and greens. Solar panels produce energy to split the stored water for the production of rocket fuel, oxygen, and for charging hydrogen fuel cells, which are necessary to power long-range vehicles as well as provide backup energy storage in case of dust storms."

The team believes that the Mars tree habitats could find a niche on Earth as well, at high latitudes, deserts and the sea floor, for example. In addition, the hydroponics technology could provide city dwellers with fresh food and the tunnels could be used to ease congestion in urban areas.

The team took out first place in the Architecture section of the 2017 Mars City Design competition